donation. 1  an act or instance of presenting something as a gift, grant, or contribution. 2  a gift, as to a fund; contribution.
A black or brown tongue typically is due to the overgrowth of bacteria that normally are present on the tongue. This, too, can be caused by the killing of some bacteria with antibiotics so other bacteria overgrow. But the most common cause of discoloration of the tongue is the overgrowth of a fungus. The most common fungus is called candida. But overgrowth of the candida fungus turns the tongue white. Infection with candida is called candidiasis, and when it happens on the tongue the condition is called thrush.
On a basic level, your tongue looks white because the papillae (fleshy raised portions of tissue lining your tongue) have become swollen for some reason. Since they are more raised, the papillae can trap tiny particles of food, dead cells from within your mouth, or bacteria between them, creating a paler hue.